What to know about the Transmission Speed Sensor:
Because both the engine and the transmission can spin at diverse speeds, it’s essential that the vehicle’s computer is able to analyze the speed of the transmission’s torque converter or input shaft. The transmission speed sensor is a magnetic sensor that delivers this information, allowing the transmission to shift smoothly. The sensor counts the internal number of revolutions of the transmission and transmits that information to the transmission control unit, where the data is used to determine the rotational speed. If the speed is too great, the gears need to be altered – it’s the same principle as watching the tachometer and shifting before the RPMs get too high while driving a vehicle with a manual transmission.
Facts to Note:
On some makes, one of the engine mounts may need to be removed to access the failed part.
Transmission speed sensors cannot be fixed only changed.
While transmission speed sensor failure is common, many other problems can present similar systems such as ABS sensor failures. A full professional inspection will be needed to determine the true cause of the problem.
How to Fix:
The transmission speed sensor is confirmed that it needs to be changed. The vehicle is lifted and supported on jack stands as required.
The transmission speed sensor is located in the transmission housing and removed.
The new transmission speed sensor is installed into the transmission housing.
The transmission speed sensor is connected. The vehicle is removed from the jack stands.
The vehicle is road tested and scanned for proper operation of the transmission speed sensor.
The transmission speed sensor isn’t a part that can be inspected during normal maintenance, nor does it have a specific service interval for replacement. If you notice abnormal shifting or speedometer readings, have one of your expert mechanics diagnose the sensor.
Common symptoms indicating you may need to change the Transmission Speed Sensor:
Transmission shifts roughly
Transmission doesn’t shift into higher gears
Speedometer and/or odometer doesn’t work
Cruise control is inoperative
Importance of this service:
With a faulty transmission speed sensor, the transmission control unit will be unable to determine the actual speed, which can make shifting gears difficult or even impossible. This will render the car unusable, so it is very vital to have the sensor changed as soon as it is determined to be defective.